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Roadmap

timeline TD
0.1.0 · 6 Jul 2026 : Core read path
                 : Header parsing, HDU enumeration
                 : Four readers, image data with cutouts
0.2.0 : Tables and Arrow
      : BINTABLE and ASCII table decode
      : @fits-js/arrow package
0.3.0 : Tile compression
      : RICE_1, GZIP_1, GZIP_2
      : Subtractive dither
0.4.0 : WCS transforms
      : Linear WCS + six projections
      : @fits-js/wcs package
0.5.0 : Render primitives
      : Stretches, z-scale, colormaps
      : @fits-js/render package
0.6.0 : Write path
      : Write primary, IMAGE, BINTABLE
      : CHECKSUM/DATASUM
0.7.0 : Verification and cross-runtime CI
      : Verify checksums
      : Strict vs lenient parse
      : Full cross-runtime CI

Shipped

Section titled “Shipped”

See the Changelog for full details on each release.

  • 0.1.0 · 6 July 2026 · core read path: header parsing, HDU enumeration, four readers, image decode with lazy cutouts

0.1.0 · Core read path

Section titled “0.1.0 · Core read path”

The lazy random-access core. One parser over four readers, image HDU support end to end.

  • Header parsing: fixed and free-format cards, CONTINUE long strings, HIERARCH long keywords, indexed access (NAXISn, TFORMn), duplicate keyword handling, lenient recovery.
  • HDU enumeration: primary and extensions, recognition of IMAGE, BINTABLE, and ASCII table extensions. Lookup by EXTNAME and EXTVER.
  • Readers: BytesReader (in-memory), BlobReader (browser Blob/File), NodeFileReader for fs-backed access, HttpRangeReader with LRU paging and If-Range.
  • Image data: readImage with region cutouts, BITPIX scaling (BZERO/BSCALE), unsigned-int convention, BLANK to NaN.

Planned

Section titled “Planned”

0.2.0 · Tables and Arrow

Section titled “0.2.0 · Tables and Arrow”

BINTABLE and ASCII table decode. Return columns as arrow.Table or RecordBatch stream so astronomy catalogs become first-class in the JS columnar ecosystem.

  • BINTABLE column decode covering L X B I J K A E D C M, repeat counts, TSCAL/TZERO/TNULL, TDIM, and P/Q variable-length arrays via the heap.
  • ASCII table decode covering fixed-width fields with TFORM and TBCOL.
  • @fits-js/arrow package: FITS column to Arrow type mapping, RecordBatch per read chunk, lazy column projection.

0.3.0 · Tile compression

Section titled “0.3.0 · Tile compression”

Transparent decode of compressed-image extensions. A compressed MAST/ESO file reads exactly like an uncompressed one.

  • Z* compressed-image keyword set and tile geometry.
  • RICE_1, GZIP_1, GZIP_2 decode.
  • Subtractive dither variants 1 and 2, byte-for-byte against funpack.

0.4.0 · WCS transforms

Section titled “0.4.0 · WCS transforms”

Real pixel-to-sky and sky-to-pixel transforms.

  • Linear model (CRPIX, CRVAL, CDELT).
  • CD and PC matrix forms.
  • TAN, SIN, ARC, ZEA, AIT, CAR projections.
  • pixel↔sky round-trip verified against astropy.wcs.
  • @fits-js/wcs package.

0.5.0 · Render primitives

Section titled “0.5.0 · Render primitives”

Pixel transforms to RGBA for canvas, without hand-rolling the astronomy stretches.

  • Linear, log, sqrt, asinh, power stretches.
  • Z-scale and percentile autoscaling.
  • Small baked colormap set (gray, viridis, magma, heat).
  • WCS grid and axis overlays as SVG paths.
  • @fits-js/render package. No UI components. Canvas wiring is the consumer’s job.

0.6.0 · Write path

Section titled “0.6.0 · Write path”

Construct and write primary, IMAGE, BINTABLE, and ASCII table HDUs with correct headers and checksums.

  • Write primary and IMAGE HDUs.
  • Write BINTABLE including the heap.
  • Write ASCII table.
  • Header construction and mutation API.
  • CHECKSUM and DATASUM generation.
  • Every read fixture round-trips and passes fitsverify clean.

0.7.0 · Verification and cross-runtime CI

Section titled “0.7.0 · Verification and cross-runtime CI”

Integrity verification, an explicit strict-vs-lenient contract, and a proven-identical cross-runtime story.

  • DATASUM and CHECKSUM verification.
  • Structural conformance check at fitsverify level.
  • The strict vs lenient contract formalized as a conformance guarantee (both modes exist since 0.1.0).
  • Full CI matrix: Node 22/24, Bun, Deno, Workers, headless browser.

Beyond 0.7.0

Section titled “Beyond 0.7.0”

Planned, not yet versioned: the PLIO_1 and HCOMPRESS_1 tile codecs, SIP and TPV distortion, spectral and time WCS, compressed BINTABLE, and a DuckDB-wasm table function.